fn for_expansion(text: &str) -> Cow<'_, str>Expand description
The text as calcard should expand it. calcard puts a changed occurrence (RECURRENCE-ID) in place of its time in the series only when both have the same SEQUENCE, where RFC 5545 matches them by RECURRENCE-ID alone: a series edited since, or an occurrence changed by an application that counts its own changes, would show twice, at its old time and its new one. So each changed occurrence is read with the series’ SEQUENCE; the file is left as it is.